As a technique for improving appearances and scratch resistance of products made of thermoplastic resins, there are known a laminated film formed by laminating a film made of thermoplastic resins with a film superior in its appearances and scratch resistance, and a laminated structure formed by laminating a substrate made of thermoplastic resins with a film superior in its appearances and scratch resistance.
With respect to the former, i.e. the laminated film, there is proposed a three-layer laminated film composed of an olefinic resin-made film, a hard acrylic resin-made film superior in its transparency and scratch resistance and an adhesive resin interposed between both films to bond them, wherein the adhesive resin is, for example, a halogen- or acid anhydride group-carrying olefinic resin, as disclosed in, for example, JPA-9-193189, JP-A-9-234836, JP-B-6-26718 and JP-B-8-2550.
With respect to the latter, i.e. the laminated structure, there is known a laminated structure obtained by injecting an olefinic resin to be molded into a substrate on an olefinic resin-made film situated so as to attach closely to an inner wall of an injection molding mold, thereby performing simultaneously both a molding of the substrate and adhesion between the substrate and the film as disclosed in, for example, JP-B-50-19132.
Each of the references referred to above is incorporated herein by reference in its entirety.
However, the former laminated film has problems such that (1) its impact resistance is lower than that of the olefinic resin made-film per se, because an acrylic resin is used, which is harder and more fragile than the olefinic resin, (2) its thickness is unduly large and its production cost is too high, because the adhesive resin has to be interposed between the acrylic resin-made film and the olefinic resin-made film, and (3) the laminated film can hardly be recycled as it is, because the acrylic resin-made film and the olefinic resin-made film are different materials in kind.
The latter laminated structure also has a problem such that the scratch resistance thereof is not satisfactory, because the olefinic resin-made film used is low in its scratch resistance.